The Science of Iodine: Every Study, Every Condition, All in One Place

By Dr. Evan Lewis, PhD

Iodine has been used in medicine for over 150 years. It predates antibiotics, predates synthetic antifungals, and predates most products in a pharmacy today. Unlike many older remedies that faded when pharmaceuticals arrived, iodine stuck around, because the clinical evidence kept supporting it.

This article is a reference hub. It gathers the published evidence on iodine's antifungal, antibacterial, antiviral, and wound-care properties in one place, explains the mechanisms behind them, and contextualizes what iodine is, and is not, in a modern clinical setting.

Section 1: Iodine and Antifungal Activity

The Mechanism

Iodine's antifungal activity operates through two primary mechanisms. First, iodine disrupts fungal cell membranes through oxidative action. Second, iodine interferes with fungal protein structures, denaturing the enzymes and structural proteins fungi require for growth and reproduction.

These mechanisms make iodine active against dermatophytes, the fungal species most commonly responsible for nail fungus (onychomycosis) and athlete's foot. Dermatophytes, including Trichophyton rubrum and Trichophyton mentagrophytes, depend on keratin as a nutrient source.

Key Research: Onychomycosis

PMC1569938: "An Economical Cure: Decolorized Iodine for Onychomycosis"

This peer-reviewed study examined the use of decolorized iodine applied daily to confirmed cases of onychomycosis. The findings showed significant clinical improvement in the treated nails.

PMC4599634: "Onychomycosis Treated with Povidone-Iodine/DMSO"

This study investigated the combination of povidone-iodine with dimethyl sulfoxide (DMSO), a penetration enhancer. The key finding was measurable clinical improvement in onychomycosis cases, with a reported 62% culture-negative rate at 24 weeks.

JAAD S0190-9622(14)00459-9, Journal of the American Academy of Dermatology

Published in the Journal of the American Academy of Dermatology, this study confirmed that a topical povidone iodine nail solution demonstrated active efficacy against dermatophyte species in controlled conditions.

Section 2: Iodine and Antibacterial Properties

The Mechanism

Iodine's antibacterial activity is one of the most well-documented properties in all of clinical microbiology. The mechanism is oxidative disruption of bacterial cell walls. Iodine is effective against both gram-positive and gram-negative bacteria and does not rely on a single receptor pathway, which is one reason bacterial resistance to iodine has not been a clinically significant issue.

Key Applications in Foot and Skin Care

Staphylococcus (shoe and foot odor): Staphylococcus species, along with Brevibacterium, are the primary bacteria responsible for foot and shoe odor.

Cutibacterium acnes (acne): Cutibacterium acnes is the bacteria primarily implicated in acne vulgaris.

Wound pathogens: Iodine has been used as a wound antiseptic in clinical settings for over 150 years.

Section 3: Iodine and Skin and Wound Care

WHO Essential Medicines

The World Health Organization's Model List of Essential Medicines includes povidone iodine for wound management. Iodine for wound care is on the WHO list because it is clinically effective, reliably available, and has a well-established safety profile.

Surgical and Post-Operative Use

Povidone iodine solutions are used globally for surgical skin preparation. The continued use of iodine-based solutions in surgical prep in major hospitals worldwide reflects its status as a clinically proven, trusted antiseptic agent.

Aqueous Iodine Advantage

Aqueous iodine, iodine stabilised in distilled water without a polymer carrier, offers the antibacterial and antifungal activity of iodine in a formulation that does not stain and is designed for daily topical use.

Section 4: Iodine and Antiviral Properties

Iodine's antiviral properties are an active area of ongoing research. Some research supports an antiviral mechanism for iodine against certain viral types at the skin surface level. In the context of daily foot hygiene, iodine's primary validated roles are antifungal and antibacterial.

Section 5: 150 Years of Clinical Use

1811: Bernard Courtois first isolates iodine from seaweed ash.

1839: First documented use of iodine as a clinical antiseptic.

1955: Povidone iodine (iodine complexed with polyvinylpyrrolidone) is developed. Betadine is introduced shortly after.

Present: Aqueous iodine formulations represent the most recent evolution: retaining clinical efficacy in a formulation suited to daily skin and footwear use without staining.

Iodine remains on the WHO Model List of Essential Medicines and is used in surgical prep in hospitals worldwide.

Section 6: What Iodine Is, and Isn't

Not a Thyroid Supplement

IodinePure's topical products are for external use. They are listed with Health Canada as cosmetics and are not intended to be ingested. They do not function as thyroid supplements. (IodinePure's separate daily supplement line is a different product category.)

Grounded in the Evidence

Iodine has well-defined antifungal, antibacterial, and antiseptic properties in specific clinical contexts. We present that science accurately, letting the mechanism, the published research, and real-world clinic adoption make the case rather than overstating beyond the evidence base.

A Partner to Professional Care

More than 200 foot care clinics across North America trust IodinePure and recommend it as part of professional care protocols, which is exactly why the science matters to practitioners putting their name behind it.

Not the Same as Betadine

Betadine uses polyvinylpyrrolidone as a carrier polymer. IodinePure uses aqueous iodine, iodine stabilised in distilled water. Aqueous iodine does not stain and is designed for daily use on skin, nails, and inside footwear.

Section 7: The IodinePure Difference

IodinePure products contain two ingredients: iodine and distilled water. No synthetic preservatives, no alcohol base, no polymer emulsifiers, no fragrance, no colorants.

EZ Clear Nails: Daily application to the nail plate. 90-day nail care protocol.

Sole Shield: Foot surface application and inside footwear after each wear.

EZ Clear Skin: Facial and body spray.

For clinic partnerships: see our clinic partner page. Trusted in 200+ foot care clinics across North America.

Frequently Asked Questions

What does iodine do topically?

When applied to skin, nails, or inside footwear, iodine acts as a broad-spectrum antiseptic with documented antifungal activity against dermatophytes and antibacterial activity against gram-positive and gram-negative bacteria.

Is iodine backed by science?

Yes. Iodine has one of the longest and most thoroughly documented evidence bases of any topical antiseptic agent. It appears on the WHO Model List of Essential Medicines and has been the subject of peer-reviewed research published in major dermatology journals.

Is topical iodine safe?

Topical iodine has a well-established safety profile for appropriate use. IodinePure products are listed with Health Canada as cosmetics for topical use. Individuals with known iodine sensitivity or thyroid conditions should consult a healthcare provider before use.